Dental Tribune Middle East & Africa Edition | 6/2018 40 TEMPLATE DESIGN © 2007 www.PosterPresentations.com A Novel Approach to Improve Repair Bond Strength of Repaired Acrylic Resin: An in-Vitro Study on the Shear Bond Strength Masoumah S. Qaw, Tahani H. Abu Showmi, Danah F. Almaskin, Zahra A. AlZaher, Mohammed M. Gad BDS, MSc, Reem Abualsaud, BDS, DScD, Fahad A. Al-Harbi BDS, MSD, DScD Introduction Denture bases are subjected to fracture if dropped or stressed beyond their fracture strength. Therefore, denture repair is needed sometimes. Many mechanical and chemical factors affect the repair strength. The aim of the study was to introduce a new approach that increases the bond strength at denture base resin/repair resin interface. This study evaluated the effect of mechanical surface treatments with intermediate material applications (alumina blasting + silane coupling agent [SCA] or methyl methacrylate [MMA]) on the shear bond strength (SBS) of repaired denture base material. It also evaluated the combined effect of nano-ZrO2 and surface treatments on the SBS of repaired acrylic denture base and compared the values with those of unreinforced PMMA resin. In addition, the treated surfaces were characterized by means of scanning electron microscope (SEM). Conclusions Heat-polymerized acrylic resin was used to fabricate 130 cylindrical blocks 15 mm in diameter. Specimens were divided into different groups according to surface treatment and NZ concentration (Figure 1). Repair resin was mixed and applied to the bonding area and polymerized at 37°C for 10 minutes. SBS (MPa) testing was performed using universal testing machine (Figure 2). Scanning electron microscopy (SEM) was used. Statistical analysis was done using ANOVA and Tukey post-hoc test at α = 0.05. Materials & Methods Results The mean bond strength value of repair resin to alumina blasted denture base specimens with application of intermediate agents was significantly higher in comparison to control group (P<0.05). For surface treatment, alumina blasting followed by SCA application, showed the highest SBS values (15.42±1.98MPa). Nano-ZrO2 addition resulted in statistically significant increase (p<0.05) except for AB, and AB+MA repaired with 5% and 7.5% nano-ZrO2 (P>0.05) (Figure 3). SEM showed that alumina blasting produced rougher and porous surface, while SCA and MA application reduced the irregularities and deep pits (Figure 4). Within the limitations of the study, following conclusions were drawn: • Mechanical surface treatment using alumina abrasive air-particles improved the shear bond strength. • SCA and Methyl methacrylate based composite bonding agent application to mechanically treated repair surfaces improved the repair bond strength and could be used as a new adhesive technique for denture repair. • Application of SCA in combination with Nano-ZrO2 reinforced repair material enhanced the repair bond strength. Figure 1: Study workflow. C=control, AB= Alumina blasting, SCA=Silane coupling agent, MA= Methyl methacrylate based composite bonding agent, NZ= Zirconium oxide nanoparticles, SEM= Scanning electron microscope Figure 2: Schematic diagram showing a specimen fixed in the jig, which is mounted on universal testing machine for shear bond testing. Figure 3. Mean, SD, and significance of all tested groups for shear bond strength values of repaired specimens (MPa) Figure 4. SEM images showing the effect of surface treatment before repair. (A) Control specimen; (B) Alumina-blasted; (C) Alumina-blasted + SCA; (D) Alumina-blasted + MA. References • Gad MM, Fouda SM, Al-Harbi FA, Näpänkangas R, Raustia A. PMMA denture base material enhancement: a review of fiber, filler, and nanofiller addition. International Journal of Nanomedicine. 2017; 12:3801-3812. • Vasthare A, Shetty S, Kamalakanth Shenoy KK, Shetty MS, Parveen KA, Shetty R. Effect of different edge profile, surface treatment, and glass fiber reinforcement on the transverse strength of denture base resin repaired with auto-polymerizing acrylic resin: An In vitro study. J Interdiscip Dentistry 2017; 7:31-7. • Gad MM. Evolution of Denture Repair and a Review of New Era. J Dental Sci 2017, 2(2): 000125. 0 5 10 15 20 25 SBS (Mpa) Shear Bond Strength- Mean and SD 1 st Place Poster Presentation Winner 10 th Dental Facial Cosmetic Conference, Dubai, UAE POSTER PRESENTATION